190 A CENTURY'S PROGRESS IN ASTRONOMY. 



Potsdam by Vogel and Lohse. It was closely 

 similar to that of the new star of 1866, bright 

 lines of hydrogen and other elements standing 

 out in front of an "absorption" spectrum. By 

 the end of 1876 the star was of the seventh 

 magnitude. On September 2, 1877, Nova Cygni 

 was observed at Dunecht, and its spectrum was 

 found to have been transformed into that of a 

 planetary nebula. Three years later, however, 

 the ordinary stellar spectrum reappeared. 



A new star appeared in the centre of the 

 great nebula in Andromeda in August 1885. 

 The first announcement of the discovery was by 

 Karl Ernst Albrecht Hartwig (born 1851), who 

 observed the new star on August 31 ; but it 

 had been previously seen by several other ob- 

 servers. On September 1 it was of the seventh 

 magnitude, and by March of the following year 

 had fallen to the sixteenth. Observed by Vogel, 

 Young, and Hasselberg, the new star gave a 

 continuous spectrum, but Huggins and Copeland 

 succeeded in discerning bright lines. Hall, at 

 Washington, undertook a series of measures to 

 detect the parallax of Nova Andromedse, but 

 his efforts were unsuccessful. 



The discovery of the next temporary star was 

 announced February 1, 1892, by the Rev. Thomas 



